Excavating device



Sept 11, 1962 G. c. coRLx-:Y 3,053,331

EXCAVATING DEVICE Filed 001).- 25, 1959 United States Patent Otllice3,@533l Patented Sept. l1, 1962 3,053,331 EXCAVA'HNG DEVIQE Gale C.Corley, 1207 Beech St., Valparaiso, lind. Filed Oct. 23, 1959, Ser. No.848,383 5 claims. (ci. 1175-202) This invention relates to an improvedearth underreamer for use in reaming the lower portions of previouslyexcavated holes or bores so that an enlarged base or footing may beprovided under poured concrete foundation piers, pilings, posts or thelike.

In certain types of construction it is common practice to use concretecolumns which extend below grade level as foundation supports for beamstructures. Good engineering practice and some building codes requirethat the bottom of such columns be enlarged to provide proper supportand prevent foundation settlement. Although various types ofunderreamers have been proposed to perform this worlr, they have beenfound to embody unduly complex and costly structures and to suffer fromsuch problems as clogging in retraction, diiicult actuation of thecutters, and high torque requirements at extended positions of thecutters. As a result, it has been common practice to enlarge holes forfoundation supports by primitive hand spades and this has been costlybecause of the hand labor required.

Accordingly, it is an object of the present invention to provide animproved underreamer having adjustable excavating means for thegraduated enlargement of a lower portion of a pre-bored foundation hole,which may be readily lowered into and withdrawn from the hole withoutinterference from the excavating means and yet which will excavate ashaped underfooting cavity having a large diameter in proportion to thediameter of the prebored hole.

Another object is to provide a hollow underreamer adapted to receive andstore the excavated material, which will not join in heavy wet soil orclay when it is desired to retract the exacavating means, and from whichthe excavated material may be easily unloaded after the underreamer isremoved from the bore hole.

A further object is to provide an underreamer having excavating meanspositively actuated in both the expanding and retracting directions andwhich may be locked in a plurality of graduated positions easilyobservable by the operator, and in which the amount of back torque beingexerted on the excavating means during the cutting operation tends toremain constant for such positions.

Still another object of the invention is the provision of a strongunderreamer having a minimum of parts and which is very simple andeconomical to construct.

A feature of the present invention is the provision of an underreamerhaving excavating means in the form of a combined cutting and deflectingmember including a base portion, which may be formed in the shape of aquarter section of a circle, and a scoop portion mounted on the circularedge thereof. The base portion is pivotally mounted at its vertex in ahorizontal position offset from the center of the casing so that thecutting member is rotatable through an opening in the side of theunderreamer casing to a plurality of extended cutting positions.

Another feature is the provision of an underreamer having a singlecutting member pivotally mounted on an axially offset longitudinal rodwhich extends the length of the casing and to which a crank arm orhandle is pivotally attached at the upper end of the rod to provideleverage for directly actuating the cutting member. The pivotable handlemay be positioned in notches provided in the upper rim of the casing tolock the cutting member in a plurality of positions, thereby providingan easily observable indication of the setting of the cutting member atall times.

A further feature of the invention is the provision of an underreamerhaving a cutting member of the aforesaid character with a cutting edgeboth on the leading edges and on the trailing edges thereof so that itslices back into the fully loaded casing With a minimum of effort.

A still further feature is the provision of an underrearner having acutting member driven by rotating the hollow casing so that it iscapable of transmitting high torsional forces without cluttering theinterior of the casing with driving apparatus obstructive to theentrance and storage of excavated material.

Still another feature is the provision of an underreamer adapted forpower operating and having helical guiding means, such as a spiralauger, iixedly mounted in the hollow casing to facilitate the elevationand storage of the excavated material during the cutting operation, andan annular flange mounted around the top of the casing to seal the topof the hole and to lock the positioning handle in visible positions.

Yet another feature is the provision of an underreamer having a trapdoor in the bottom thereof to facilitate emptying the underreamer andwhich is locked by retracting the cutting member and is thereforecontrolled by actuating the positioning rod.

The invention is illustrated in the accompanying drawing in which:

FIG. l is a perspective view of an underreamer constructed in accordancewith the invention;

FIG. 2 is a fragmentary perspective view of the lower portion of theunderreamer illustrating the manner in which it operates in a pre-boredhole;

FIG. 3 is a bottom plan view of the underreamer;

FIG. 4 is a fragmentary elevational view of a lower portion of theunderreamer taken in section on line 4 4 of FIG. 3; and

FIG. 5 is a perspective view of another embodiment of the inventionadapted for operation by a power driving unit.

An underreamer provided in accordance with the invention includes ahollow, elongated cylindrical casing having a cutting member retractabletherein. The cutting member includes a vertical scoop-like blade mountedon the circular edge of a horizontal radial blade, the latter beingconnected at its vertex to a positioning rod so that the cutting memberis pivotable through an opening provided in the side of the casing. Thelongitudinal positioning rod is pivotally mounted along the side of thecasing. A handle is pivotally connected to an upper portion of thepositioning rod for positively actuating and positioning the cuttingmember located at the bottom of the casing. The bottom of the casing isenclosed by a plate having a hinged trap door therein which is latchedby actuating the cutting member. In a power driven embodiment of theinvention a spiral auger is mounted within the casing to elevateexcavated soil, and an annular flange is fastened to the upper edge ofthe casing to prevent the elevated soil from spilling into the borehole. A plurality of spaced pegs or lugs mounted on the upper surface ofthe flange receive and lock the handle in various visible positions,while a plurality of notches in the upper edge of the casing may servethis function when the flange is not used.

Referring now to the drawing, FIG. 1 shows an underreamer embodying theinvention and adapted for hand operation. A hollow casing 11 shaped inthe form of an elongated cylinder is provided having7 a suitablediameter and length to slidably fit within a pre-bored hole of a givensize. The casing should be tall enough to extend a sufficient distanceabove the surface of the earth to permit convenient hand operation. Apair of opposite holes 12 are located near the upper end of casing 11 toreceive a pipe or bar 13 for use in rotating the casing by hand. Theupper end of casing 11 is left open while the lower end of the casing isenclosed by a circular bottom plate 14.

An excavating or cutting member consisting of a horizontal blade portion16, shaped generally in the form of a sector of a circle, and a verticalscoop-like blade portion 17, is rotatably mounted inside the casingadjacent bottom plate 14. The side of casing 11 adjacent the excavatingmember is cut out so that an opening 1S is provided of a size and shapeto permit the excavating member to pivot therethrough (FIG. 2). Cuttingedges, such as knife edge 19, are provided on the leading and trailingoutwardly extending edges of blade portion 16 as indicated at 16a and16b (FIGS. 1, 2 and 3). Similarly, cutting edges are provided at theleading edge 17a and the trailing edge 17b of the scoop-like bladeportion 17.

The vertex of blade 16 is secured to the lower end of a vertical shaftor rod 21 which is pivotally mounted on bottom plate 14 near the insidesurface of the casing and which extends longitudinally to the top of thecasing. The upper end of rod 21 is rotatably mounted in a suitablebearing bracket 22 welded to the inner wall of the casing. An uprightarm 23 is fastened or welded to the' upper portion of rod 21 topivotally support a handle 24. A portion of the upper edge of casing 11,disposed generally opposite bracket 22, is cut into a plurality ofspaced notches 26 which are adapted to receive and position handle 24.

As may be more clearly seen in FIGS. 3 and 4, the bottom plate 14 isdivided into two portions; a rigid portion 14a welded to the inside wallof casing 11 and a larger portion 14b pivotally secured to portion 14aby a pair of hinges 27 to form a trap door opening downwardly from thebottom of casing 11. Trap door 14b carries an L- shaped lug 28 welded toits upper inside surface at a point where it will be engaged by `a wedgeZ9, fastened to the bottom outside edge of blade 17, in the fullyretracted position of the cutting member.

In operation, a conventional post hole digger or other hole drillingequipment is employed to dig a hole of the desired depth and diameter.Then an underreamer, constructed to t this hole and embodying thestructure of the invention, is lowered into the pre-bored hole. Thecutting member blades 16 and 17 are fully retractable within casing 11(FIG. l) so that it can bear against the sides of the hole and thusserve as a guiding sleeve for accurate underreaming. Pipe handle 13 maybe centered in casing holes 12 to provide handles on either side ofcasing 11 for lowering the underreamer into the hole.

With the casing bottom plate 14 resting against the bottom of the hole,the blades of the cutting member are extended through opening 18 so asto bite into the earthen side wall of the hole. Extension of the cuttingmember is accomplished at the upper end of the casing by merely liftinghandle 24 upward out of a notch 26 and moving it clockwise, causing rod21, horizontal blade 16 and scoop blade 17 to rotate clockwise. It willbe seen that the plurality of spaced notches in cooperation with handle24 provide a graduated locking mechanism for the cutter. If a shallowcut is desired, then handle 24 is dropped into the next adjacent notch,thus locking the cutting member in a slightly extended positioncoresponding to this notch setting. This setting is used, for instance,in hard soil or clay. Then casing 11 is rotated one complete revolutionin a clockwise direction, as indicated by the arrows in FIG. 1. Sincethe excavating mechanism is non-rotatably mounted with respect to thecasing, the blades rotate with the casing. The material excavated fromthe side wall of the hole, commonly referred to as spoi1, is deflectedinto the hollow interior of casing 11 by scoop 17. Due to the fact thatthe casing itself is used for transmitting torque, there is a maximumamount of spoil storage space available within the casing.

After the rst cut has been made, the cutting member is further extendedby moving handle 24 clockwise to the next adjacent notch, and the casingis rotated once more. This process is continued until the blades arefully extended (FIG. 2) and an underfooting cavity 30 is completelyexcavated. In loose soil, such as sand, larger bites are possible andtherefore some of the intermediate notches and corresponding cuttersetting need not be used.

It is to be understood that cutting members of various shapes andmaterial may be provided for interchangeable use with the underreamer ofthe invention. In the disclosed embodiment, the horizontal'blade 16 hasa leading knife edge 19. A similar shape is given to the leading edge ofthe scoop 17. In addition, scoop 17 is quarter cylindrical in shape,conforming to the outer edge of quarter circular blade 16 (FIG. 3).

Both members combine to form the correct geometric configuration to cuta bell-shaped cavity 30 at the bottom of the hole (FIG. 2). It is wellknown that an underfooting of this shape provides the greatest strengthin proportion to its mass. Of course, other cavity shapes may beproduced by varying either the shape of scoop 17 or the combined shapeof blade 16 and scoop 17.

Since vertical scoop blade 17 pivots from rod 21 on a. center which isoffset from the axial center of casing 11, the radius of horizontalblade 16 may be almost as large as the diameter of the casing. Thismakes it possible to excavate an underfooting cavity having a largediameter compared to the diameter of the pre-bored hole, thus effectingconsiderable savings in the amount of concrete needed to support a givenweight. It is also to be noted that the angle of incidence of theleading edge of scoop 17 with the side of the hole is most abrupt or atits maximum when the cutting member is least extended.

When the cutting member is fully extended the leading edge of scoop 17is approximately tangential to the periphery of the cavity. Thus therake angle of the vertical blade Varies inversely with the depth of thecut, and consequently the back torque exerted on the cutting member bythe material being excavated tends to remain constant.

Once the underfooting cavity has been completed, handle 24 is unlockedand returned counter-clockwise to its original position, therebyretracting the cutting member completely within the casing. The trailingedges of both horizontal blade 16 and vertical blade 17 are alsosharpened to a knife edge so that they will easily slice into the spoilaccumulated within casing 11. Retraction is further facilitated by theleverage provided by handle 24, another important feature whenexcavating in wet, heavy clay.

During the cutting operation trap door 14b is unlocked, but since it isresting on the bottom of the hole no spoil can escape. Then as scoop 17is retracted, wedge 29 engages the L-shaped lug 28 to cam the doortightly closed. Hence, by locking the cutting member in the fullyretracted position (by dropping handle 24 in the first notch), theoperator automatically locks the trap closed. The casing is then liftedfrom the hole by means of handle 13 and rested on the xed bottom portion14a. Trap door 14b may then be unlocked to dump the spoil by movinghandle 2,4 clockwise one notch. Cooperation is thus achieved between thecutter actuating-locking mechanism and the trap door latch, with theoperation and condition of both being readily indicated to the operatorby the position of the handle 24 at the top of the casing.

In FIG. a modified underreamer in accordance with the invention is shownadapted for power operation. Those elements identical with the elementsof the abovedescribed embodiment are given identical reference numeralsand their description not repeated. A helicoidal guide or auger 31 isnon-rotatably mounted within casing 11 to elevate spoil from the bottomto the top of the casing as the casing is rotated. A central shaft 32 iswelded to the auger blades to support an adapter coupling 33 carried onthe upper end of the shaft. The adapter coupling may also be braced bysupporting legs 34. The chuck of a conventional portable air motor 36 isreceived in the upper end of the adapter coupling to power drive theunderreamer.

A large annular flange 37 is secured to the upper edge of casing 11 tokeep the elevated spoil from falling back into the excavated hole. Aplurality of positioning elements, such as spaced pegs 38, are welded onthe upper surface of the flange in lieu of the easing notches 26. Handle24 is again pivotally secured to positioning rod 21, but now extendsoutwardly to be received and locked between pegs 38. The outer edge ofthe flange extends beyond the end of handle 24 so that it will notendanger the operator when the underreamer is rotating. Trap door 14 mayalso be provided on the bottom of the underreamer, but it need only beused for iinal cleaning of the underreamer since spoil is automaticallyejected by the spiral auger. Since positioning rod 21 is normallydisposed closely adjacent the inside wall of casing 11, there is nomechanism within casing 11 to interfere with the elevation of spoil. Itwill thus be seen that this embodiment possesses all the advantagesobtained by the structure of the first embodiment, and only a fewadditional elements are necessary to readily convert the hand operatedunderreamer for efcient high speed operation.

I claim:

l. In an underreamer for excavating an underfooting cavity in a pre-dughole, and which underreamer includes a vertically extending, hollowelongated cylindrical casing and means for rotating the casing in agiven direction, and with the casing having an opening in its side withleading and trailing edges with respect to the given direction ofrotation; the combination including longitudinally extending shaft meansrotatably supported within the casing on a substantially vertical axisnear the leading edge of the opening, a cutting member shaped to passthrough the opening and having a horizontal portion generally in theform of a sector of a circle, with the apex thereof pivotally mounted onsaid shaft means and with cutting edges formed along both edgesextending outwardly from the apex, said cutting member having a curvedscoop portion extending vertically from said horizontal portion anddisposed substantially in an arc spaced from said axis with cuttingedges formed along the leading and trailing edges of said scoop portion,and means for rotating said shaft means to thereby pivot said cuttingmember so that said sector portion and said scoop portion travel throughsaid opening with said scoop portion passing near the trailing edge ofthe opening, said cutting member when extending through said openingbeing positioned to undercut the pre-dug hole upon rotation lof thecasing and being retractable into the casing for withdrawal of thecasing from the excavation.

2. The combination of claim l further including helical guide meansmounted inside the casing and extending through the length thereof, saidguide means elevating spoil produced by said cutting member uponrotation of the casing.

3. In an underreamer having a vertically extending elongated hollowcylindrical casing adapted for rotation in a given direction, with thecasing having an opening in its side having leading and trailing edges,the combination of a cutting member having a horizontal portion shapedsubstantially in the form of a sector of a circle and having cuttingedges formed along both edges extending outwardly from the vertexthereof, said cutting member also having a scoop portion disposedvertically along the circular edge of said horizontal portion withcutting edges formed along the leading and trailing edges of said scoopportion, shaft means rotatably supported within the casing on asubstantially Vertical axis near the leading edge of the opening in thecasing, said horizontal portion of said cutting means being connected atthe vertex thereof to said shaft means, means coupled to said shaftmeans for rotating the same to position said cutting member, saidcutting member being movable to a position in which it extends throughsaid opening and being retractable completely within the casing, andmeans for rotating the casing in the given direction whereby saidcutting member when eX- tending through said opening undercuts a pre-dughole in which the underreamer is placed.

4. An underreamer for excavating an underfooting cavity in a pre-sunkhole including in combination, a hollow, elongated cylindrical casinghaving an opening in its side near the bottom thereof, a plate enclosingthe bottom of said casing below said opening, bearing means secured tothe inside of said casing near the top thereof, a positioning rodextending the length of said casing and being rotatably supported bysaid plate and said bearing means in a position parallel to and offsetfrom the axis of said casing, a cutting member having a horizontal bladeshaped substantially in the form of a sector of a circle with cuttingedges formed along both edges extending outwardly from the vertexthereof, said cutting member also having a vertical scoop blade securedto the circular edge of said horizontal blade with cutting edges formedalong the leading and trailing edges of said scoop blade, said cuttingmember being secured to said rod at the vertex of said horizontal bladeand adjacent said opening so that said cutting member is extendible andcompletely retractable through said opening, a handle pivotallyconnected to the upper end of said rod for actuating said cuttingmember, said casing having a plurality of spaced notches along the upperedge thereof adapted to receive said handle to lock said cutting memberin a plurality of corresponding angular positions, said plate having ahinged trap door therein for emptying spoil from said casing, said scoopblade having a wedge portion on the yback side thereof, said trap doorhavinga locking portion adapted to -receive said Wedge portion so thatsaid trap door is locked closed in rthe retracted position of saidcutting member and means for rotating said casing in a given directionwhereby Said cutting member undercuts the pre-dug hole when extendedthrough said opening in said casing.

5. A power driven underreamer for excavating an underfooting cavity in apre-sunk hole including in combination, a hollow, elongated cylindricalcasing having an opening in its side near the bottom thereof, a platemounted in said casing below said opening, bearing means secured to theinside of casing near the top thereof, a positioning rod longitudinallyextending along the inner surface of said casing and being pivotallysupported by said plate and said bearing means, a cutting member havinga horizontal blade shaped substantially in the form of a sector of acircle With cutting edges formed along both edges extending outwardlyfrom the vertex thereof and having a vertical scoop blade secured to thecircular edge of said horizontal blade with cutting edges formed alongthe leading and trailing edges of said scoop blade, said excavatingmeans being secured to said rod at the vertex of said horizontal bladeand adjacent said opening so that the cutting member is extendible andcompletely retractable through said opening, a handle pivotallyconnected tothe upper end of said rod for actuating said cutting member,an annular ange secured to the upper edge of said casing and having aplurality of spaced lugs thereon adapted to receive said handletherebetween to lock said cutting member in a plurality of correspondingangular positions, said plate having a hinged trap door therein foremptying spoil from said casing, said scoop blade having a wedge portionon the back side thereof, said trap door having a locking portionadapted to receive said wedge portion so that said trap door is lockedclosed in the retracted position of said cutting member, means securedto the top of said casing and adapted to couple a power drive unitthereto for rotating said casing and a spiral auger References Cited inthe le of this patent UNITED STATES PATENTS 207,122 Julien Aug. 20, 18781,905,995 Bertran Apr. 25, 1933 2,621,898 Brodhead et al Dec. 16, 19522,912,225 Kandle Nov. l0, 1959 2,912,228 Kandle Nov. 10, 1959

